Radiocesium-bearing microparticles cause a large variation in Cs activity concentration in the aquatic insect (Tricoptera: Stenopsychidae) in the Ota River, Fukushima, Japan

Ishii, Yumiko*; Miura, Hikaru*; Jo, J.*; Tsuji, Hideki*; Saito, Rie; Koarai, Kazuma; Hagiwara, Hiroki; Urushidate, Tadayuki*; Nishikiori, Tatsuhiro*; Wada, Toshihiro*; et al.

PLOS ONE (Internet), 17(5), p.e0268629_1 - e0268629_17, 2022/05

https://doi.org/10.1371/journal.pone.0268629

We investigated the variability in Cs activity concentration in individual aquatic insects in detritivorous caddisfly () and carnivorous dobsonfly () larvae from the Ota River, Fukushima. Caddisfly larvae showed sporadically higher radioactivity, whereas no such outliers were observed in dobsonfly larvae. Autoradiography and scanning electron microscopy analyses confirmed that these caddisfly larvae samples contained radiocesium-bearing microparticles (CsMPs), which are insoluble Cs-bearing silicate glass particles. CsMPs were also found in potential food sources of caddisfly larvae, such as periphyton and drifting particulate organic matter, indicating that larvae may ingest CsMPs along with food particles of similar size. Although CsMPs distribution and uptake by organisms in freshwater ecosystems is relatively unknown, our study demonstrates that CsMPs can be taken up by aquatic insects.

Damped soft phonons and diffuse scattering in (BiNa)TiO

Matsuura, Masato*; Iida, Hiroyuki*; Hirota, Kazuma*; Owada, Kenji; Noguchi, Yuji*; Miyayama, Masaru*

Physical Review B, 87(6), p.064109_1 - 064109_10, 2013/02

https://doi.org/10.1103/PhysRevB.87.064109

Neutron-scattering studies of (BiNa)TiO (BNT) have been performed to elucidate the microscopic mechanism of the broad maximum in the temperature dependence of the dielectric constant at Tm 600 K and the reduction in the piezoelectric properties above the depolarization temperature, 460 480 K. We observed diffuse scattering near the point below 700 K, which competes with the superlattice peak at the M point of the tetragonal phase but coexists with the superlattice peak at the R point of the rhombohedral phase. The diffuse scattering shows an anisotropic Q shape extending along the 100 direction transverse to the scattering vector Q, which is explained by atomic shifts bridging the tetragonal and rhombohedral structures. We propose that the broad maximum in the dielectric constant is associated with a diffusive first-order transition between the competing tetragonal and rhombohedral phases. In addition, we found that the diffuse scattering is reduced for single crystals grown under high oxygen pressure, which suggests an analogy with the central peak in hydrogen-reduced SrTiO. Inelastic neutron scattering near the point reveals a heavily overdamped soft mode similar to those reported in lead-based relaxors, the "waterfall" feature. Moreover, a damped soft transverse acoustic mode is observed for the 100 direction as the anisotropic diffuse scattering, indicating phase instabilities with the same origin as that of the diffuse scattering. The recovery of the soft mode is observed near the depolarization temperature, which coincides with the disappearance of the superlattice peak at the M point. These results indicate that the depolarization and the waterfall feature originate in the dynamic nature of ferroelectric clusters in the coexisting tetragonal/rhombohedral phase.

Effect of B-site randomness on the antiferroelectric/relaxor nature of the ground state; Inelastic X-ray scattering study of Pb(InNb)O

Owada, Kenji; Fukuda, Tatsuo; Mizuki, Junichiro; Hirota, Kazuma*; Terauchi, Hikaru*; Tsutsui, Satoshi*; Baron, A. Q. R.*; Owa, Hidehiro*; Yasuda, Naohiko*

Journal of the Korean Physical Society, 59(3), p.2509 - 2514, 2011/09

https://doi.org/10.3938/jkps.59.2509

Pb(InNb)O (PIN) can be antiferroelectric (AFE), ferroelectric (FE) or a relaxor depending upon the perovskite B-site randomness. Orderd PIN (O-PIN, without B-site randomness) is supposed to be an ideal system of lead-based complex perovskite Pb(B'B'')O and expected to give us a clear picture of the AFE/relaxor nature of the ground state by the B-site randomness. We studied the dynamics of O-PIN by inelastic X-ray scattering. The quasielastic (QE) scattering shows the critical slowing down and the transverse acoustic (TA) mode shows the softening towards . On the other hand, the transverse optic (TO) mode shows the softening toward low temperature with no clear anomaly at . These results represent that the antiferroelectric (AFE) phase transition is associated with the TA and the origin of the QE scattering, while ferroelectric correlation does exist behind the AFE ordering. The effect of B-site randomness is finally discussed on the basis of the results.

Uncertainty reduction of hydrologic models using data from surface-based investigation

Karasaki, Kenji*; Ito, Kazumasa*; Wu, Y.*; Shimo, Michito*; Sawada, Atsushi; Maekawa, Keisuke; Hatanaka, Koichiro

Proceedings of TOUGH Symposium 2009 (Internet), 9 Pages, 2009/09

Intrinsic ferroelectric instability in Pb(InNb)O revealed by changing B-site randomness; Inelastic X-ray scattering study

Owada, Kenji; Hirota, Kazuma*; Terauchi, Hikaru*; Fukuda, Tatsuo; Tsutsui, Satoshi*; Baron, A. Q. R.*; Mizuki, Junichiro; Owa, Hidehiro*; Yasuda, Naohiko*

Physical Review B, 77(9), p.094136_1 - 094136_8, 2008/03

https://doi.org/10.1103/PhysRevB.77.094136

Antiferroelectric (AFE), ferroelectric (FE) or relaxor states can appear in Pb(InNb)O (PIN) depending upon the perovskite B-site randomness. We studied the effects of this randomness on the dynamics of PIN by high resolution inelastic X-ray scattering using ordered PIN (AFE) and disordered PIN (relaxor) single crystals. We have found a clear softening of a transverse optic mode at the point in both the samples, indicating a robust and intrinsic ferroelectric instability regardless of the actual ground state. We interpret that AFE is stabilized only when In and Nb ions are spatially ordered enough to overwhelm the FE instability. As the B-site randomness becomes larger, AFE is suppressed and the hidden FE state starts appearing. Ultimately, the randomness begins to predominate over the development of FE regions and blocks a long range FE order, which we believe yields polar nanoregions resulting in relaxor behaviors.

Spatial distribution of the B-site inhomogeneity in an Pb(InNb)O single crystal studied by a complementary use of X-ray and neutron scatterings

Owada, Kenji; Hirota, Kazuma*; Terauchi, Hikaru*; Owa, Hidehiro*; Yasuda, Naohiko*

Journal of the Physical Society of Japan, 75(2), p.024606_1 - 024606_6, 2006/12

https://doi.org/10.1143/JPSJ.75.024606

Structural properties of Pb(InNb)O (PIN) single crystals at room temperature (RT) were investigated by X-ray and neutron scattering techniques, taking much account of the difference in the penetration depth and spatial resolution of X-rays and those of neutrons. A strong diffuse scattering was observed by X-ray while h/4, k/4, 0 superlattice reflections were found by neutron, indicating a relaxor state in the outer-layer of the crystal and an antiferroelectric (AFE) state in the bulk. The phonon dispersion was measured for the first time for the PIN series. Two transverse optic (TO1 and TO2) modes were clarified near the zone center though neither water-fall behavior nor folding of phonon branches was confirmed. We have thus concluded that a major part of the PIN crystal at RT is ferroelectric (FE). These results imply that the -site chemical ordering, i.e. inhomogeneity, which controls the structural properties of PIN, is unevenly distributed throughout the crystal. We speculate that small AFE grains coexist with the FE matrix while the outer-layer is in a relaxor state in the PIN.

Rice plants take up iron as an Fe-phytosiderophore and as Fe

Ishimaru, Yasuhiro*; Suzuki, Motofumi*; Tsukamoto, Takashi*; Suzuki, Kazumasa*; Nakazono, Mikio*; Kobayashi, Takanori*; Wada, Yasuaki*; Watanabe, Satoshi; Matsuhashi, Shimpei; Takahashi, Michiko*; et al.

Plant Journal, 45(3), p.335 - 346, 2006/02

https://doi.org/10.1111/j.1365-313X.2005.02624.x

Training report of the FBR cycle training facility in 2004FY

Watanabe, Toshio; Ozawa, Kazumasa; Otsuka, Jiro; Sasaki, Kazuichi; Sawada, Makoto

JNC TN4440 2005-001, 34 Pages, 2005/07

JNC-TN4440-2005-001.pdf:1.85MB

no abstracts in English

Training report of the FBR cycle training facility in 2004FY

Watanabe, Toshio; Ozawa, Kazumasa; Otsuka, Jiro; SASAKI, Kazuhito; Sawada, Makoto

JNC TN4410 2004-003, 39 Pages, 2004/07

JNC-TN4410-2004-003.pdf:0.66MB

The FBR cycle training facility consists of sodium handling training facility and maintenance training facility, and is being contributed to train for the operators and maintenance workers of the prototype fast breeder reactor "Monju". So far, some training courses have been added to the both training courses of sodium handling technologies maintenance technologies in every year in order to carry out be significant training for preparation of Monju restarting. As encouragement of the sodium handling technology training in 2003FY, the sodium heat transfer basic course was equipped as the 9th sodium handling training course with the aims of learning basic principal technology regarding sodium heat transfer. While, for the maintenance training course, a named "Monju Systems Learning Training Course", which aims to learn necessary knowledge as the engineers related Monju development, was provided newly in this year as an improvement concerned the maintenance course. In 2003FY, nine sodium handling technology training courses were carried out total 33 times and 235 trainees took part in those training courses. Also, nine training courses concerning the maintenance technology held 15 times and total 113 trainees participated. On the other hand, the 4th special lecture related sodium technology by France sodium school instructor was held on Mar. 15-17 and 34 trainees participated. Consequently, a cumulative trainees since October in 2000 opened the FBR cycle training facility reached to 1,236 so for.

Neutron diffraction study of field-cooling effects on the relaxor ferroelectric Pb[(ZnNb)Ti]O

Owada, Kenji; Hirota, Kazuma*; Rehrig, P. W.*; Fujii, Yasuhiko*; Shirane, Gen*

Physical Review B, 67(9), p.094111_1 - 094111_8, 2003/03

https://doi.org/10.1103/PhysRevB.67.094111

High-temperature () and high-electric-field () effects on Pb[(ZnNb)Ti]O (PZN-8%PT) were studied comprehensively by neutron diffraction in the ranges ~K and ~kV/cm. We have focused on how phase transitions depend on preceding thermal and electrical sequences. In the field cooling process (FC, ~kV/cm), a successive cubic (C) tetragonal (T) monoclinic (M) transition was observed. In the zero field cooling process (ZFC), however, we have found that the system does transform to the rhombohedral (R) phase as widely believed, but to a new, unidentified phase, which we call X. X gives a Bragg peak profile similar to that expected for R, but the -axis is always slightly shorter than the -axis. As for field effects on the X phase, it transforms into the M phase via another monoclinic phase (M) as expected from a previous report [Noheda , 224101 (2002)].